1. Field Of The Invention
The invention relates to a process for the production of 2-hydroxy-3-halo-5-nitropyridines.
2. Background Art
Due to the reactive functional groups, 2-hydroxy-3-halo-4-nitropyridines are universally applicable for active ingredient syntheses for pharmaceutical agents or herbicides. For example, 2,3-dichloro-5-nitropyridine, obtained by chlorination according to Chemical Abstracts, 70:106327x, [T. Batkowski, Rocz. Chem., 42, (2), (1968), pp. 2079 to 2088], can be used for synthesis of herbicides according to German OS 3,545,570. According to Chemical Abstracts, 70:106327x, [T. Batkowski. Rocz. Chem., 42, (2), (1968), pp. 2079 to 2088], it was known to produce 2-hydroxy-3-chloro-5-nitropyridine, starting from 2-amini-5-nitropyridine, by chlorination to 2-amino-3-chloro-5nitropyridine (yield 29 percent) and by subsequent diazotation/saponification of the amino group (yield 72 percent). The unfavorable yields as well as the very difficulty of obtaining feedstock 2-amino-3-chloro-5-nitropyridine are disadvantages of such process.